Let's roll up our sleeves and solve this. We have 788 and we're going to multiply it by 28, essentially adding 788 to itself 28 times.
Step 1: 0 + 788 = 788
Step 2: 788 + 788 = 1576
Step 3: 1576 + 788 = 2364
Step 4: 2364 + 788 = 3152
Step 5: 3152 + 788 = 3940
Step 6: 3940 + 788 = 4728
Step 7: 4728 + 788 = 5516
Step 8: 5516 + 788 = 6304
Step 9: 6304 + 788 = 7092
Step 10: 7092 + 788 = 7880
Step 11: 7880 + 788 = 8668
Step 12: 8668 + 788 = 9456
Step 13: 9456 + 788 = 10244
Step 14: 10244 + 788 = 11032
Step 15: 11032 + 788 = 11820
Step 16: 11820 + 788 = 12608
Step 17: 12608 + 788 = 13396
Step 18: 13396 + 788 = 14184
Step 19: 14184 + 788 = 14972
Step 20: 14972 + 788 = 15760
Step 21: 15760 + 788 = 16548
Step 22: 16548 + 788 = 17336
Step 23: 17336 + 788 = 18124
Step 24: 18124 + 788 = 18912
Step 25: 18912 + 788 = 19700
Step 26: 19700 + 788 = 20488
Step 27: 20488 + 788 = 21276
Step 28: 21276 + 788 = 22064

So, 788*28 = 22064